In high-performance digital audio equipment such as compact disk players and digital tape or cassette recorders, the total dynamic behavior of the digital-to-analog conversion system plays an important role. This imposes strong demands on the digital-to-analog converter (DAC) design, such as oversampling capabilities and stereo-signal handling. To realize low power consumption in DAC design, CMOS technology is suitable. However, traditional CMOS DACs are expensive to fabricate.
K. Maio, et al., An Untrimmed D/A Converter with 14-Bit Resolution, IEEE J. Solid-States Circuits, Vol. SC-16, No. 6, December 1981 discloses a 14-bit DAC with more than 16-bit linearity that is useable in high fidelity digital audio systems and precision measuring equipment. That paper describes a monolithic DAC which uses a new compensation technique for the DAC linearity, called the "self-compensation technique". The DAC of the Maio paper compensates for linearity error by a calibration technique which references to a ramp function with about 17-bit linearity, thus avoiding the trimming of analog components. Although the DAC of the Maio article provides a linearity error of less .+-.1/2 LSB and settling time of 1-2 .mu.sec, it yet suffers from two significant limitations. First of all, use of the calibration ramp function requires a very low dielectric absorption integrating capacitor that causes monotonicity problems at the MSB transition points. Secondly, the Maio DAC uses 5 LSBs and 3 sub-LSBs to correct only the 5 MSB error.
Thus, there is a need for a simple, low-cost, low-power consumption digital-to-analog converter to provide sufficient accuracy for 16-bit digital-to-analog conversion.
There is a need for a 16-bit digital-to-analog converter that provides minimal circuit die size for very linear output characteristics, including absolute gain.
Moreover, there is a need for 16-bit digital-to-analog converter that provides total dynamic performance, accuracy, and reliability in the 16-bit regime.
Additionally, there is the need for a 16-bit digital-to-analog converter that provides good monotonicity at the most significant bit transition points while at the same time providing 1/2 least significant bit differential linearity over the entire output range.